We have migrated our app from Xcode 6.4 to Xcode 7 and Swift 2. The app uses CoreData with 2 MOCs and was working well without any multithread violations warning. And now, compiling from Xcode 7, under devices or simulators running iOS 8.4 and 8.3 we get the famous "Multithreading_Violation_AllThatIsLeftToUsIsHonor". It works well on devices running any iOS 9 and iOS 8 before 8.3. And also works well with Xcode 6.4 and all iOS versions.
Xcode 6.4 = Works well on all iOS
Xcode 7 = Breaks on 8.3 and 8.4 only
We have checked our code and I think it's all OK.
The line that fires the error is result = [context executeFetchRequest:request error:&error];
- (void)getActiveUserWithCompletion:(void (^)(User *user))completion {
NSManagedObjectContext *context = [[CoreDataManager singleton] getInsertContext];
NSManagedObjectContext *mainContext = [[CoreDataManager singleton]getContext];
__block NSError * error = nil;
__block NSArray *result = [NSArray array];
[context performBlock:^{
NSFetchRequest *request= [[NSFetchRequest alloc] init];
[request setEntity: [NSEntityDescription entityForName:K_COREDATA_USER inManagedObjectContext:context]];
[request setPredicate:[NSPredicate existToken]];
[request setFetchLimit:1];
result = [context executeFetchRequest:request error:&error];
if ( result.count == 1 ) {
User *user = result.firstObject;
NSManagedObjectID *moid = [user objectID];
[mainContext performBlock:^{
User *activeUser = (User *)[mainContext existingObjectWithID:moid error:&error];
completion(activeUser);
}];
}else if ( result.count > 1 ) {
completion(nil);
}else {
completion(nil);
}
}];
}
Predicate code:
+ (NSPredicate *)existToken{
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"sessionToken != nil"];
return predicate;
}
A very similar error is on Apple dev forums without any working solution: Apple Developer forum
Any advice or solution is welcome.
